TOI-1266 c
TOI-1266 c is a mini-Neptune orbiting the M2 star TOI-1266 in the constellation Draco. It lies about 118 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is TOI-1266 c?
TOI-1266 c has a radius of 1.98 times that of Earth. Its mass is 3.2 times that of Earth, giving it a density of 2.25 g/cm³ — between that of rocky and gaseous planets.
Is TOI-1266 c in the Habitable Zone?
TOI-1266 c orbits inside the inner edge of the habitable zone of TOI-1266. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-1266: 0.133–0.343 AU (conservative: 0.168–0.325 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on TOI-1266 c
The equilibrium temperature of TOI-1266 c is about 346 K (73 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C.
Orbit and Year Length
A year on TOI-1266 c — one full orbit around TOI-1266 — lasts 18.8 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.105 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.07).
How Was TOI-1266 c Discovered?
TOI-1266 c was discovered in 2020 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is TOI-1266 c?
TOI-1266 c is 117.5 light-years (36.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1909. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,068,000 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. TOI-1266 c scores 0.68, ranking #75 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-1266
TOI-1266
- Spectral type
- M2
- Surface temperature
- 3,563 K (Sun: 5,772 K)
- Mass
- 0.44 M☉
- Radius
- 0.42 R☉
- Luminosity
- 0.0263 L☉
- Age
- 4.6 billion years (Sun: 4.6)
The TOI-1266 Planetary System
TOI-1266 c is one of 3 known planets in the TOI-1266 system. Its siblings:
- TOI-1266 b (Mini Neptune)
- TOI-1266 d (Super Earth)
TOI-1266 c — Complete Data
| Radius | 1.980 Earth radii (0.177 Jupiter radii) |
|---|---|
| Mass | 3.17 Earth masses (0.010 Jupiter masses) |
| Density | 2.25 g/cm³ (Earth: 5.51) |
| Orbital period | 18.80 days |
| Orbital distance | 0.105 AU |
| Eccentricity | 0.071 |
| Equilibrium temperature | 346 K (73 °C) |
| Earth Similarity Index | 0.68 |
| Distance from Earth | 117.5 light-years (36.0 parsecs) |
| Constellation | Draco |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2025-03-21. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1266 c
Is TOI-1266 c habitable?
No — TOI-1266 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-1266 c?
TOI-1266 c is about 118 light-years from Earth in the constellation Draco. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,068,000 years to get there.
How big is TOI-1266 c compared to Earth?
TOI-1266 c has 1.98 times the radius of Earth and about 3.2 times its mass.
How long is a year on TOI-1266 c?
One orbit around TOI-1266 takes 18.8 Earth days — short enough that 19 of its years would fit into one Earth year.
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